The volcanic Spert Island lies off the western extremity of Trinity Island in the Palmer Archipelago close to the Antarctic Peninsula. Spert Arch (above) is a large arch with a span of about 40 feet and a height of about 60 feet. The arch, eroded from volcanic basalt, is located about mid-island on the west coast (see printable sketch map). Explorer Arch (below), also made of basalt, has two openings. The main opening is about 60 feet wide and about 60 feet high. It is located at the southern end of the island. Photos by Ray Millar.